There are 1.1 million persons living with HIV (PLWH) in the US, 60% of them smoke cigarettes, and 75% of them are interested in quitting. Two-thirds of them use the internet. Almost none are currently accessing smoking cessation interventions designed to meet their specific needs and concerns. Cigarette smoking is responsible for 24% of deaths among PLWH, and 30% of non-AIDS defining malignancies. It is driving the alarming rise in lung cancers in this highly vulnerable population. The lack of access to proven, effective, culturally appropriate tobacco cessation services represents a health disparity of the first order. The psychosocial profile of the PLWH-smoker community, characterized by high rates of psychiatric comorbidity, drug and alcohol use, and low levels of social support, suggests that achieving high cessation rates will be a great challenge. Positively Smoke Free on the Web is the first web-based cessation program developed expressly for PLWH smokers. It is a resource that is ready for clinical use, but its feasibility and efficacy have yet to be studied. The main goals of this proposal are (1) to evaluate the website's feasibility (i.e. recruitment, adherence, retention, and satisfaction) in a cohort of 69 PLWH smokers, and (2) to complete a prospective, randomized controlled trial comparing the efficacy of the online program to standard care (total N=138) with a primary outcome of 3 month point-prevalence abstinence. If the program is proven to be efficacious, the project will have short term impact by offering a broadly available, free option for tobacco treatment to an underserved, high-priority population, and by informing further research on the optimization of web-based treatment for PLWH smokers. The long-term impact will be reduced tobacco-related morbidity and mortality among PLWH, and a clearer understanding of the role of targeted, web-based health interventions in comprehensive HIV care.